The commission in 2000 gave permission to Edison to use a rail line to move the reactor. But the utility said that building a spur to the line and covering other costs would be too expensive.

Commission member Pedro Nava complained on Friday that Edison was looking for the least costly choice. "This is like a guy who built a yacht in his basement and couldn't figure out how to get it out the door," he said.

Mark Massara, a representative of the Sierra Club, told the commission that San Onofre's operators were behaving like "reckless pennypinchers."

But Edison officials argued the beach was often used by Marines for training. The commission also noted that Marine vehicles often travel the same stretch of beach.

Massara said the Sierra Club intends to offer a live Webcast of the move to allow public monitoring.